Generate the asset pipeline directories

...to be used with Sprockets (already bundled in RailsAPI as a
dependency of ActionPack)
Copy in the vendored asset files
Setup the directory structure for our Ember app
Setup the load order
Hmm… smell that coffee...
Beef up the dependencies

There are two gems to take note of:

* `ActiveModelSerializers` is a project that is written by the `Ember`
core team which will normalize the `JSON` output for models in a
`Rails` app.
* `HandlebarsAssets` will allow the `AssetPipeline` to compile
`Handlebars` templates which is required for Ember. There is the
`Ember-Rails` gem which will also do this but @bcardarella found
HandlebarsAssets to be a leaner solution.